Bypass valve for a water circulation system

ABSTRACT

A bypass valve includes a housing having a hot water port configured to communicate with a hot water supply line and a return port configured to discharge water from the housing for recirculation to a hot water source. The housing has a passage permitting recirculating flow between the hot water port and the return port. A valve member is operable to allow and restrict recirculating flow through the passage. The valve member restricts water flow through the passage in a failed state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/977,827, filed Dec. 23, 2010, which is a continuation of U.S. patentapplication Ser. No. 11/594,470, filed Nov. 8, 2006 issued as U.S. Pat.No. 7,874,498 on Jan. 25, 2011, which claims the benefit of provisionalpatent No. 60/850,171, filed Oct. 5, 2006 and which is acontinuation-in-part of U.S. patent application Ser. No. 11/172,681,filed Jul. 1, 2005, issued as U.S. Pat. No. 7,140,382 on Nov. 28, 2006,which was a divisional of U.S. patent application Ser. No. 10/006,970,filed Dec. 4, 2001, issued as U.S. Pat. No. 6,929,187, on Aug. 16, 2005,which is a continuation-in-part of U.S. patent application Ser. No.09/697,520 filed Oct. 25, 2000, issued as U.S. Pat. No. 6,536,464 onMar. 25, 2003, and claimed priority to U.S. Provisional Application No.60/251,122 filed Dec. 5, 2000, the complete subject matter from all ofwhich is expressly incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to faucets and bypass valves foruse in home or industrial water distribution systems that supply waterto various fixtures at different temperatures through different pipes.More particularly, the present invention relates to faucets havingbypass valves that are thermostatically controlled so as toautomatically bypass water that is not at the desired temperature foruse at the fixture. Even more particular, the present invention relatesto faucets having an integral thermostatically controlled bypass valve.

2. Background

Home and industrial water distribution systems distribute water tovarious fixtures, including sinks, bathtubs, showers, dishwashers andwashing machines, that are located throughout the house or industrialbuilding. The typical water distribution system brings water in from anexternal source, such as a city main water line or a private water well,to the internal water distribution piping system. The water from theexternal source is typically either at a cold or cool temperature. Onesegment of the piping system takes this incoming cold water anddistributes it to the various cold water connections located at thefixture where it will be used (i.e., the cold water side of the faucetat the kitchen sink). Another segment of the piping system delivers theincoming cold water to a water heater which heats the water to thedesired temperature and distributes it to the various hot waterconnections where it will be used (i.e., the hot water side of thekitchen faucet). At the fixture, cold and hot water either flow throughseparate hot and cold water control valves that are independentlyoperated to control the temperature of the water into the fixture bycontrolling the flow rate of water from the valves or the water is mixedat a single valve that selectively controls the desired temperatureflowing into the fixture.

A well known problem common to most home and industrial waterdistribution systems is that hot water is not always readily availableat the hot water side of the fixture when it is desired. This problem isparticularly acute in water use fixtures that are located a distancefrom the hot water heater or in systems with poorly insulated pipes.When the hot water side of these fixtures is left closed for some time(i.e., overnight), the hot water in the hot water segment of the pipingsystem sits in the pipes and cools. As a result, the temperature of thewater between the hot water heater and the fixture lowers until itbecomes cold or at least tepid. When opened again, it is not at alluncommon for the hot water side of such a fixture to supply cold waterthrough the hot water valve when it is first opened and for some timethereafter. At the sink, bathtub or shower fixture located away from thewater heater, the person desiring to use the fixture will either have touse cold or tepid water instead of hot water or wait for thedistribution system to supply hot water through the open hot watervalve. Most users have learned that to obtain the desired hot water, thehot water valve must be opened and left open for some time so that thecool water in the hot water side of the piping system will flow outahead of the hot water. For certain fixtures, such as dishwashers andwashing machines, there typically is no method of “draining” away thecold or tepid water in the hot water pipes prior to utilizing the waterin the fixture.

The inability to have hot water at the hot water side of the fixturewhen it is desired creates a number of problems. One problem is havingto utilize cold or tepid water when hot water is desired. This is aparticular problem for the dishwasher and washing machine fixtures inthat hot water is often desired for improved operation bf thosefixtures. As is well known, certain dirty dishes and clothes are mucheasier to clean in hot water as opposed to cold or tepid water. Even inthose fixtures where the person can let the cold or tepid water flow outof the fixture until it reaches the desired warm or hot temperature,there are certain problems associated with such a solution. One suchproblem is the waste of water that flows out of the fixture through thedrain and, typically, to the sewage system. This good and clean water iswasted (resulting in unnecessary water treatment after flowing throughthe sewage system). This waste of water is compounded when the person isinattentitive and hot water begins flowing down the drain and to thesewage system. Yet another problem associated with the inability to havehot water at the hot water valve when needed is the waste of time forthe person who must wait for the water to reach the desired temperature.

The use of bypass valves and/or water recirculation systems in home orindustrial water distribution systems to overcome the problems describedabove have been known for some time. The objective of the bypass valveor recirculation system is to avoid supplying cold or tepid water at thehot water side of the piping system. U.S. Pat. No. 2,842,155 to Petersdescribes a thermostatically controlled water bypass valve, shown asFIG. 2 therein, that connects at or near the fixture located away fromthe water heater. In his patent, the inventor discusses the lack of hotwater problem and describes a number of prior art attempts to solve theproblem. The bypass valve in this patent comprises a cylindrical housinghaving threaded ends that connect to the hot and cold water piping atthe fixture so as to interconnect these piping segments. Inside thehousing at the hot water side is a temperature responsive element havinga valve ball at one end that can sealably abut a valve seat. Thetemperature responsive element is a metallic bellows that extends whenit is heated to close the valve ball against the valve seat andcontracts when cooled to allow water to flow from the hot side to thecold side of the piping system when both the hot and cold water valvesare closed, Inside the housing at the cold water side is a dual actioncheck valve that prevents cold water from flowing to the hot water sideof the piping system when the hot water valve or the cold water valve isopen. An alternative embodiment of the Peters' invention shows the useof a spiral temperature responsive element having a finger portion thatmoves left or right to close or open the valve between the hot and coldwater piping segments. Although the invention described in the Peters'patent relies on gravity or convection flow, similar systems utilizingpumps to cause a positive circulation are increasingly known. Thesepumps are typically placed in the hot water line in close proximity tothe faucet where “instant” hot water is desired.

U.S. Pat. No. 5,623,990 to Pirkle describes a temperature-controlledwater delivery system for use with showers and eye-wash apparatuses thatutilize a pair of temperature responsive valves, shown as FIGS. 2 and 5therein. These valves utilize thermally responsive wax actuators thatpush valve elements against springs to open or close the valves to allowfluid of certain temperatures to pass. U.S. Pat. No. 5,209,401 toFiedrich describes a diverting valve for hydronic heating systems, bestshown in FIGS. 3 through 5, that is used in conjunction with athermostatic control head having a sensor bulb to detect the temperatureof the supply water. U.S. Pat. No. 5,119,988 also to Fiedrich describesa three-way modulating diverting valve, shown as FIG. 6. A non-electric,thermostatic, automatic controller provides the force for the modulationof the valve stem against the spring. U.S. Pat. No. 5,287,570 toPeterson et al. discloses the use of a bypass valve located below a sinkto divert cold water from the hot water faucet to the sewer or a waterreservoir. As discussed with regard to FIG. 5, the bypass valve is usedin conjunction with a separate temperature sensor,

A recirculating system for domestic and industrial hot water heatingutilizing a bypass valve is disclosed in U.S. Pat. No. 5,572,985 toBenham. This system utilizes a circulating pump in the return line tothe water heater and a temperature responsive or thermostaticallyactuated bypass valve disposed between the circulating pump and the hotwater heater to maintain a return flow temperature at a level below thatat the outlet from the water heater. The bypass valve, shown in FIG. 2,utilizes a thermostatic actuator that extends or retracts its stemportion, having a valve member at its end, to seat or unseat the valve.When the fluid temperature reaches the desired level, the valve isunseated so that fluid that normally circulates through the return lineof the system is bypassed through the circulating pump.

Despite the devices and systems set forth above, many people still haveproblems with obtaining hot water at the hot water side of fixtureslocated away from the hot water heater or other source of hot water.Boosted, thermally actuated valve systems having valves that aredirectly operated by a thermal actuator (such as a wax filled cartridge)tend not to have any toggle action. Instead, after a few on-off cycles,the valves tend to just throttle the flow until the water reaches anequilibrium temperature, at which time the valve stays slightly crackedopen. While this meets the primary function of keeping the water at aremote faucet hot, leaving the valve in a slightly open condition doespresent two problems. First, the lack of toggle action can result inlime being more likely to build up on the actuator because it isconstantly extended. Second, the open valve constantly bleeds a smallamount of hot or almost hot water into the cold water piping, therebykeeping the faucet end of the cold water pipe substantially warm. Iftruly cold water is desired (i.e., for brushing teeth, drinking, ormaking cold beverages), then some water must be wasted from the coldwater faucet to drain out the warm water. If the bypass valve isequipped with a spring loaded check valve to prevent siphoning of coldwater into the hot water side when only the hot water faucet is open,then the very small flow allowed through the throttled-down valve maycause chattering of the spring loaded check valve. The chattering can beavoided by using a free floating or non-spring loaded check valve, it isalso detrimental to have any noticeable crossover flow (siphoning) fromhot to cold or cold to hot with any combination of faucet positions,water temperatures, or pump operation.

U.S. Pat. No. 6,536,464 the disclosure of which is incorporated hereinas fully set forth and having some of the same inventors and the sameassignee as the present invention, describes an under-the-sinkthermostatically controlled bypass valve and water circulating systemwith the bypass valve placed at or near a fixture (i.e., under the sink)to automatically bypass cold or tepid water away from the hot water sideof the fixture until the temperature of the water reaches the desiredlevel. The system described in U.S. Pat. No. 6,536,464 includes a singlesmall circulating pump that is placed between the water heater and thefirst branching in the hot water supply line which supplies the fixturehaving a bypass valve so as to pressurize the hot water piping systemand facilitate bypassing of the cold or tepid water.

The public is accustomed to purchasing faucets for lavatories, bathtubs,showers, kitchen sinks and etc. that can be readily repaired, usually byremoving a top mounted handle and bonnet, and replacing a faucet washeror other seal or seat. In recent designs, the sealing action occurswithin a replaceable cartridge, which can be easily replaced by the homerepair person. None of the known prior art devices include the use of anintegral thermostatically controlled bypass valve to bypass water asdescribed above. However, for a thermal bypass valve to be included in afaucet, it is necessary that it meet the same expectation for ease ofrepair as the standard faucet. There are several advantages to locationof the thermal bypass valve within the faucet itself and beingaccessible from the top, which include: (1) elimination of the clutterresulting from extra hoses located below the sink and the need to doplumbing and maintenance below the sink; (2) elimination of theunder-the-sink hoses, which by their very presence add potential leakpaths at each end of each hose; (3) a new feature that a faucetmanufacturer can use to define its top-of-the-line faucet, which canstimulate sales to those customers who like to have the latest inconvenience; and (4) the bypass valve can be serviced by the home repairperson or, if desired, professional plumber in a standing position in amanner which is already learned from the maintenance of existing designfaucets.

SUMMARY OF THE INVENTION

In one aspect, a bypass valve is provided including a housing having ahot water port configured to communicate with a hot water supply lineand a return port configured to discharge water from the housing forrecirculation to a hot water source. The housing has a passagepermitting recirculating flow between the hot water port and the returnport. A valve member is operable to allow and restrict recirculatingflow through the passage. The valve member restricts water flow throughthe passage in a failed state.

In another aspect, a bypass valve for use in a bypass path of a watercirculation system is provided having a valve member operable to allowand restrict recirculating flow through the passage. The valve memberrestricting water flow through the passage in a failed state. The bypassvalve also includes a control mechanism in the bypass path of the watercirculation system. The control mechanism is used for controlling theoperation of the valve unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a water distribution system that utilizes a water controlfixture (faucet) having a thermostatically controlled bypass valve ofthe present invention;

FIG. 2 is a side view of the preferred thermally sensitive actuatingelement, shown in its unmodified condition, for use in the bypass valveof the present invention;

FIG. 3 is a front view of a typical fixture body for a single handlefaucet;

FIG. 4 is a side view of the single handle faucet in FIG. 3;

FIG. 5 is a top view of the faucet body housing for the faucet of FIG.3;

FIG. 6 is a side cross-sectional view of the faucet body housing for thefaucet of FIG. 3;

FIG. 7 is a bottom view of the faucet body housing of the faucet of FIG.3;

FIG. 8 is a sectional view of a bypass valve cartridge body for use withthe present invention;

FIG. 9 is a sectional view of the bypass valve cartridge body taken at90 degrees to FIG. 8;

FIG. 10 is a sectional view of the bypass valve cartridge body of FIG. 8with a bypass valve and other components place therein;

FIG. 11 is a cross-sectional view of the side of a shower faucet thatutilizes a cartridge insert (not shown) for controlling the flow ofwater through the faucet showing the placement of a bypass valvetherein;

FIG. 12 is a cross-sectional view of the side of a modified ball controlmechanism for use in single handle faucets;

FIG. 13 is a top view of the ball of FIG. 12;

FIG. 14 is a side view of the ball of FIG. 12;

FIG. 15 is a cross sectional view of modified replaceable cylindricalvalving cartridge used in some faucets as adapted for the presentinvention;

FIG. 16 is a side view of a valve member used with dual handle, singlespout faucets:

FIG. 17 is side cross-sectional view of the upper half of a cartridgeplaced in the valve member of FIG. 16;

FIG. 18 is chart showing the operational characteristics of the bypassvalve of the present invention when in use with a water distributionsystem; and

FIG. 19 is a side cross-sectional view of a modified thermal actuatorshowing modifications to reduce problems with lime buildup.

FIG. 20 is a side elevation view showing a water circulation system andfixture utilizing a bypass valve in accordance with an exemplaryembodiment.

FIG. 21 is a side elevation view of the bypass valve shown in FIG. 20 ina first state with a portion of a body of the bypass valve cutaway toillustrate the various components of the bypass valve.

FIG. 22 is a side elevation view of the bypass valve shown in FIG. 21 ina second state.

FIG. 23 is a side elevation view of the bypass valve shown in FIG. 21 ina third state.

FIG. 24 is a side elevation view of an alternative bypass valve for usewithin the water distribution system shown in FIG. 20 with a portion ofa body of the bypass valve cutaway to illustrate the various componentsof the bypass valve.

FIG. 25 is a schematic view of an alternative bypass valve for usewithin the water distribution system shown in FIG. 20.

FIG. 26 a side elevation view of an alternative bypass valve for usewithin the water distribution system shown in FIG. 20 with a portion ofa body of the bypass valve cutaway to illustrate the various componentsof the bypass valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures where like elements have been given likenumerical designations to facilitate the reader's understanding of thepresent invention, the preferred embodiments of the present inventionare set forth below. The enclosed figures and drawings are illustrativeof the preferred embodiments and represent a preferred way ofconfiguring the present invention. Although specific components,materials, configurations and uses are illustrated, it should beunderstood that a number of variations to the components and to theconfiguration of those components described herein and in theaccompanying figures can be made without changing the scope and functionof the invention set forth herein.

In the accompanying drawings of the various preferred embodiments of awater control fixture of the present invention, the water controlfixture is shown as faucet 10. However, other water control fixtures maybe adaptable to the thermal bypass valve features described herein(i.e., solenoid valve used on home laundry washing machines). A typicalwater distribution system 12 utilizing faucet 10 of the presentinvention is illustrated in FIG. 1. The water distribution system 12typically comprises a supply of cold water 14, such as from a city mainor water well, that supplies cold water directly to faucet 10 throughcold water line 16 and water to hot water heater 18 so that it may heatthe water and supply hot water to faucet 10 through hot waterline 20.Cold water line 16 connects to faucet 10 through cold water inlet 22 andhot water line 20 connects to faucet 10 through hot water inlet 24, asexplained in more detail below.

The preferred system 12 of the present invention utilizes a smallcirculating pump 26 of the type used in residential hot water spaceheating. A very low flow and low head pump is desirable because a larger(i.e., higher head/higher flow) pump mounted at the typical domesticwater heater 18 tends to be noisy. This annoying noise is oftentransmitted by the water pipes throughout the house. In addition, if theshower (as an example) is already in use when pump 26 turns on, whetherthe first start or a later cyclic turn-on, the sudden pressure boost inthe hot water line 20 from a larger pump can result in an uncomfortableand possibly near-scalding temperature rise in the water at the showerhead or other fixture in use. The smaller boost of a “small” pump (i.e.,one with a very steep flow-head curve) will result in only a very smalland less noticeable increase in shower temperature. In the preferredembodiment, the single, small pump 26 needs to provide only a flow ofapproximately 0.3 gpm at 1.0 psi pressure. In accordance with pumpaffinity laws, such a “small” pump requires a very small impeller or lowshaft speed. The inventors have found that use of a very small impelleror low shaft speed also precludes formation of an air bubble in the eyeof the impeller, which bubble may be a major cause of noise. Such asmall steep curve pump may, however, constitute a significant pressuredrop in the hot water tine 20 when several fixture taps are openedsimultaneously (such as a bathtub and the kitchen sink). To avoidreduced flow in those installations having a relatively low volume pump,a check valve 28 can be plumbed in parallel with pump 26 or incorporatedwithin the pump housing, to pass a flow rate exceeding the pump'scapacity around pump 26. When pump 26 is powered and flow demand is low,check valve 28 prevents the boosted flow from re-circulating back to itsown inlet. With check valve 28 plumbed around pump 26, it isadvantageous to place an orifice 30 in the pump discharge to provide asimple manner to achieve the desired very steep flow-head curve fromavailable stock pump designs. A single pump 26 located at or near thewater heater 18 in its discharge piping will boost the pressure in thehot water pipes somewhat above that in the cold water pipes (i.e.,perhaps one to three feet of boost). With this arrangement only one pump26 per plumbing system (i.e., per water heater 18) is required with anyreasonable number of remote faucets 10 (i.e., the typical number used inresidences) equipped with bypass valves. This is in contrast to thosesystems that require multiple pumps, such as a pump at each fixturewhere bypassing is desired.

If desired, pump 26 can operate twenty-four hours a day, with most ofthe time in the no flow mode. However, this is unnecessary and wastefulof electricity. Alternatively, pump 26 can have a timer 32 to turn onthe pump 26 daily at one or more times during the day just before thoseoccasions when hot water is usually needed the most (for instance formorning showers, evening cooking, etc.) and be set to operatecontinuously for the period during which hot water is usually desired.This still could be unnecessary and wasteful of electricity. Anotheralternative is to have the timer 32 cycle pump 26 on and off regularlyduring the period when hot water is in most demand. The “on” cyclesshould be of sufficient duration to bring hot water to all remotefixtures 10 that are equipped with a bypass valve, and the “off periodwould be set to approximate the usual time it takes the water in thelines to cool-down to minimum acceptable temperature. Yet anotheralternative is to equip pump 26 with a normally closed flow switch 34sized to detect significant flows only (i.e., those flows that are muchlarger than the bypass valve flows), such as a shower flowing. Forsafety purposes, the use of such a switch 34 is basically required if acyclic timer 32 is used. The switch 34 can be wired in series with themotor in pump 26. If the switch 34 indicates an existing flow at themoment the timer calls for pump 26 to be on, the open flow switch 34will prevent the motor from starting, thereby avoiding a sudden increasein water temperature at the fixture 10 (i.e., particularly if it is ashower) being utilized. The use of such switch 34 accomplishes severaluseful objectives, including reducing electrical power usage andextending pump life if hot water is already flowing and there is no needfor the pump to operate, avoiding a sudden temperature rise and thelikelihood of scalding that could result from the pump boost if water isbeing drawn from a “mixing” valve (such as a shower or single handlefaucet) and allowing use of a “large” pump (now that the danger ofscalding is eliminated) with its desirable low pressure drop at highfaucet flows, thereby eliminating the need for the parallel check valve28 required with a “small” pump.

By using a time-of-day control timer 32, pump 26 operates to maintain“instant hot water” only during periods of the day when it is commonlydesired. During the off-cycle times, the plumbing system 12 operatesjust as if the faucet 10 having bypass valves and pump 26 were not inplace. This saves electrical power usage from pump operation and, moreimportantly, avoids the periodic introduction of hot water intorelatively un-insulated pipes during the off-hours, thereby saving thecost of repeatedly reheating this water. The time-of-day control alsoavoids considerable wear and tear on pump 26 and the bypass valve infaucet 10. Considerable additional benefits are gained by using a cyclictimer 32, with or without the time-of-day control. In addition to savingmore electricity, if a leaky bypass valve or one not having toggleaction is used, there will be no circulating leakage while the pump 26is cycled off, even if the valve fails to shut off completely.Therefore, a simple (i.e., one not necessarily leak tight) valve maysuffice in less demanding applications. Having the leakage reduced tojust intermittent leakage will result in reduced warming of the coldwater line 16 and less reheating of “leaking” re-circulated water.

The bypass valve assemblies 36 utilized with the present invention havea thermally sensitive actuating element 38, an example of which is shownin FIG. 2, for thermostatically controlling bypass valve 36. Actuatingelement 38 is preferably of the wax filled cartridge type, also referredto as wax motors, having an integral poppet rod member 40, as best shownin FIG. 2. Rod member 40 comprises poppet 42 attached to piston 44 withan intermediate flange 46 thereon. The end of poppet 42 is configured toseat directly against a valve seat or move a shuffle (i.e., spool orsleeve valves) so as to close a passage. These thermostatic controlelements 38 are well known in the art and are commercially availablefrom several suppliers, such as Caltherm of Bloomfield Hills, Mich. Thebody 48 of actuating element 38 has a section 50 of increased diameter,having a first side 52 and second side 54, to seat against a shoulder orlike element in a valve body. Piston 44 of rod member 40 interconnectspoppet 42 with actuator body 48. Actuating element 38 operates based ontemperature to open and close the bypass valve assembly 36. For example,the actuating element 38 may expand and contract based on temperature.In one embodiment, the bypass valve assembly 36 closes when theactuating element 38 expands and the bypass valve assembly 36 opens whenthe actuating element 38 contracts. Alternatively, the bypass valveassembly 36 opens when the actuating element 38 expands and the bypassvalve assembly 36 closes when the actuating element 38 contracts. In anexemplary embodiment, the actuating element 38 comprises a blend ofwaxes or a mixture of wax(es) and metal powder (such as copper powder)enclosed in actuator body 48 by means of a membrane made of elastomer orthe like. Upon heating the wax or wax with copper powder mixtureexpands, thereby pushing piston 44 and poppet 42 of rod member 40 in anoutward direction. Upon cooling, the wax or wax/copper powder mixturecontracts and rod member 40 is pushed inward by a bias spring untilflange 46 contacts actuator body 48 at actuator seat 56. Although othertypes of thermal actuators, such as bi-metallic springs and memoryalloys (i.e., Nitinol and the like) can be utilized in the presentinvention, the wax filled cartridge type is preferred because the waxcan be formulated to change from the solidus to the liquid state at aparticular desired temperature. The rate of expansion with respect totemperature at this change of state is many times higher, resulting inalmost snap action of the wax actuating element 38. The temperature setpoint is equal to the preset value, such as 97 degrees Fahrenheit,desired for the hot water. This is a “sudden” large physical motion overa small temperature change. As stated above, this movement is reacted bya bias spring that returns rod member 40 as the temperature falls.

Because the bypass valve 36 has little or no independent “toggleaction,” after a few cycles of opening and closing, the valve tends toreach an equilibrium with the plumbing system, whereby the bypass valve36 stays slightly cracked open, passing just enough hot water tomaintain the temperature constantly at its setting. In particularplumbing systems and at certain ambient conditions, this flow is justunder that required to maintain a spring loaded check valve crackedcontinuously open. In such a situation, the check valve chatters with anannoying buzzing sound. To avoid this occurrence, the spring may beremoved from the check valve, leaving the poppet free floating. In theevent that the hot water is turned full on at a time when the bypassvalve 36 is open, thereby lowering the pressure in the hot water line20, and so inducing flow from the cold water line 16 through the openbypass valve 36 to the hot side, the free-floating poppet will quicklyclose. There is no necessity for a spring to keep this check valveclosed prior to the reversal in pressures.

Although not entirely demonstrated in early tests, it is believed thatbeneficial “toggle” action can be achieved with a bypass valve 36 ofvery simple mechanical design. If the motion of the thermal actuator 38is made to lag behind the temperature change of the water surrounding itby placing suitable insulation around the actuator 38 or by partiallyisolating it from the water, then instead of slowly closing only toreach equilibrium at a low flow without reaching shutoff, the watertemperature will rise above the extending temperature of the insulatedactuator 38 as the valve approaches shutoff, and the piston 44 will thencontinue to extend as the internal temperature of the actuator 38catches up to its higher surrounding temperature, closing the valve 36completely. It is also believed that an insulated actuator 36 will beslow opening, its motion lagging behind the temperature of thesurrounding cooling-off water from which it is insulated. When actuatingelement 38 finally begins to open the valve 36 and allow flow, theresulting rising temperature of the surrounding water will again, due tothe insulation, not immediately affect it, allowing the bypass valve 36to stay open longer for a complete cycle of temperature rise. Such an“insulated” effect may also be accomplished by use of a wax mix that isinherently slower, such as one with less powdered copper or otherthermally conductive filler. An actuator 38 to be installed withinsulation can be manufactured with a somewhat lower set pointtemperature to make up for the lag, allowing whatever valve 36 closingtemperature desired.

An additional benefit of utilizing pump 26 in system 12 is that shut-offof a toggle action valve upon attainment of the desired temperature isenhanced by the differential pressure an operating pump 26 provides. Ifpump 26 continues to run as the water at the faucet 10 cools down, thepump-produced differential pressure works against re-opening a poppettype bypass valve 36 in faucet 10. If pump 26 operates cyclically,powered only a little longer than necessary to get hot water to faucet10, it will be “off before the water at valve 36 cools down. When theminimum temperature is reached, the thermal actuator 38 will retract,allowing the bias spring to open valve 36 without having to fight apump-produced differential pressure. By-pass flow will begin with thenext pump “on” cycle. An additional benefit to the use of either atime-of-day or cyclic timer 32 is that it improves the operating life ofthermal actuator 38. Because use of either timer 32 causes cyclictemperature changes in valve 36 (as opposed to maintaining anequilibrium setting wherein temperature is constant and the actuator 38barely moves), there is frequent, substantial motion of the piston 44 inthermal actuator 38. This exercising of actuator 38 tends to prevent thebuild-up of hard water deposits and corrosion on the cylindrical surfaceof actuator piston 44 and face of poppet 42, which deposits could renderthe valve 36 inoperable.

Also inside valve 36 can be an over-travel spring (not shown) disposedbetween the first side 52 of the actuator body 48 and a stop locatedinside valve 36 to prevent damage to a fully restrained actuator 38 ifit were heated above the bypass valve's maximum operating temperatureand to hold the actuator 38 in place during operation without concernfor normal tolerance. Use of an over-travel spring, which is notnecessary for spool-type valves, allows movement of the actuator body 48away from the seated poppet 42 in the event that temperature risessubstantially after the poppet 42 contacts its seat. Without thisrelief, the expanding wax could distort its copper can, destroying thecalibrated set point. The over-travel spring also holds the bias spring,rod member 40 and actuator body 48 in place without the need to adjustfor the stack-up of axial tolerances. Alternatively, actuator 38 can befixedly placed inside valve 36 by various mechanisms known in the art,including adhesives and the like. Over-travel spring, if used, can beheld in place by various internal configurations commonly known in theart, such as a molded seat.

As there are a great many configurations and brands of faucets 10, thereare several different preferred designs of bypass valve 36 placement andarrangement to accommodate these many faucet configurations. Forpurposes of illustrating the present invention, various specificexamples are set forth below. The following examples are representativeof the types of uses to which the integral or in-faucet bypass valve 36is suitable. The examples are for illustrative purposes only and are notintended to restrict the invention to particular uses, sizes ormaterials used in the examples.

For instance, there are several basic types of faucet assemblies,including those that have a single handle faucet assembly that mixes thehot and cold water and delivers a flow of water out the single spoutbased on the user's movement of the faucets valve assembly. Anothercommon type of faucet assembly is the dual handle, single spout faucetassembly that has separate handles for the hot and cold water. As withthe single handle assembly, the hot and cold water are mixed prior tothe spout based on the user's selection of the amount of flow of hotand/or cold water. A third, older arrangement is the use of completelyseparate faucets for hot and cold water. Although the differentmanufacturers of faucets may utilize different arrangements of valvingcomponents, different valving mechanisms and/or different valves towater supply line connections, the bypass valve system of the presentinvention is adaptable to all such known configurations. As set forthbelow, the primary selection in the use of the bypass faucet assembly ofthe present invention is whether to place the bypass valve in astationary portion of the faucet, such as the hot water piping leadingto the faucet or in a housing or block portion of the faucet, or toplace the bypass valve in the moveable valving of the faucet. Selectionof which location to place the bypass valve assembly will often bedictated by economics, preferences, limitations on the amount of spaceavailable, the current design of the faucet and/or the willingness tochange.

Example 11 Single Handle Faucets w/ Bypass Valve in Stationary Block

As is well known, single handle faucets, an example of which is shown asfixture body 60, faucet 10 without its decorative covering, in FIGS. 3and 4, have both hot 24 and cold 22 water inlets connected to a housingor block 62. Various internal valving means, such as pivoting androtating ball 64, selectively and adjustably control the volume andtemperature of the flow of water by connecting the hot 20 and cold 16lines, through hot and cold conduits 66 and 68 respectively (as shown inFIGS. 5 and 7), to a single outlet spout 70 through spout outlet 72. Insuch designs, the thermal bypass valve 36 is preferably assembled intoan easily replaceable cartridge 74, shown best in FIGS. 8, 9 and 10,that can be located within the hot water conduit 66 of fixture body 60(if the design provides such access) or in an added cavity 76 placedbetween and connected to the hot 24 and cold 22 inlets, as shown in FIG.7. In either case, the bypass valve 36 senses and is controlled by thetemperature of the “hot” water in the fixture body 60. When the “hot”water is cooled off due to long disuse, the bypass valve 36 will open,providing a conduit between the hot 24 and cold 22 inlets. If the hotwater line pump 26 is then turned on, the boosted pressure in the hotwater line 20 will produce flow through the open bypass valve 36,bringing “hot” water to the fixture body.

In the above-mentioned arrangements, the flow of water from both hot 20and cold 16 lines remains unimpeded due to the previously mentionedinternal valving arrangement of the fixture body 60. The flow from thehot line 20 through the bypass valve cartridge 74 to the cold line 16 isprovided through molded or cast passages or cross-drilled holes,discussed below.

The single handle faucet body 60 with spherical ball valving means 64,shown in FIGS. 3 and 4, is a good example of a faucet design that can beeasily and economically re-designed to include a bypass valve cartridge74 in the stationary housing 62. Use of this approach requires a newfixture body 60 to be installed, with a top-accessible, suitably sizedcavity 76 to hold the bypass cartridge 74 and connect conduits 66 and 68built into the fixture body 60 to accommodate the bypassed flow from thehot 20 to the cold ′16 lines. FIGS. 5 through 7 show a modified andlengthened version of a Delta housing 62 that is used with the standardDelta faucet outer housing. The portion 78 above line AA (i.e., to theleft of in FIG. 6) it is essentially an original Delta housing, with theaddition of bore 76. Below AA (i.e., to the right of in FIG. 6) isextension 80. In the preferred use of the present invention, thesesections 78 and 80 would be made in a single, integral housing 62.Cavity 76 and the drilled and plugged cross passages 82 and 84 areadded, and the top bore 86 is extended inward if and as much as isneeded to accommodate any necessary devices, such as a ring or washer tohold cartridge assembly 74 in place in cavity 76. Drilled passage 82connects the cold water supply to cavity 76 near its top and drilledpassage 84 connects the hot water line 20 to cavity 76 near its bottom.

FIGS. 8 and 9 show the bypass valve cartridge 74, without its internalcomponents, that is designed and configured to fit in cavity 76. FIG. 10shows the components, including thermal actuator 88, assembled togetheras they would fit into cavity 76. The thermal actuator 88 is a modifiedversion of the actuator 38 that is used in U.S. Pat. No. 6,536,464 andshown in FIG. 2 herein. Water from hot water line 20 is carried throughdrilled hole 84 to the lower end of cavity 76 and flows up around andthrough the cartridge 74 to and through the open valve seat 90 (poppet42 is shown closed into against O-ring 92 forming seat 90 in FIG. 10)into the check valve chamber 94 housing check valve 96 and out throughthe cross drilled hole 98 into an annulus 100 on the cartridge 74. Fromannulus 100, between O-rings 102 and 104, the water flows throughdrilled passage 82 to the cold water supply. When sufficient water hasflowed through the bypass valve 36 to exhaust the cooled-off water inthe hot water supply line 20 and bring hot water to the bypass valve 36,the thermal actuator 88 will cause piston 44 to extend, forcing poppet42 into seat 90 to close off the flow. The seat 0-ring 92 is held inplace by spring 106, which doubles as the bias or poppet return spring.In the preferred embodiment, thermal actuator 88 is held in place by asnap fit into the split cartridge 74, which is designed to be easilymoldable. The check valve 96 is included to prevent flow of cold waterinto the hot side when the hot water is turned full on in the system, orthe equivalent usage of hot water, resulting in a lowered pressure onthe hot side. The cartridge 74 can be held down in cavity 76 by a brassring, or the like, which is in turn held down by the screw-on bonnet,which also captures the existing ball valving assembly 64.

Another example of a single handle water control fixture is shown as 110in FIG. 11. This fixture 110 is a modified Moen shower valve thatcomprises a rear housing 112 attached to the rear 114 of Moen housing116. Housing 116 has a hot water inlet port 118 and a cold water inletport 120 for receiving hot and cold water, respectively, from the hot 20and cold 16 water lines and a valve cavity 122 for receiving theoperating valve (not shown) through valve opening 124. The operatingvalve controls the flow of hot and cold water out of the spoutassociated with valve 110. Rear housing 112 has a cavity 126 configuredto hold cartridge 127 and hot 128 and cold 130 water channels to allowpassage of water around valve cavity 126 until the hot water reaches thedesired temperature to cause actuator 38 to push piston 44 rearwarduntil poppet 42 engages valve seat 90 to shut-off hot water flow throughhot water channel 128, thereby ending the diversion of “hot” water tothe cold water channel 130. Elastomeric washer shaped diaphragm 125 actsas a check valve to prevent back flow of cold to hot when hot water linepressure is reduced. Conical washer shaped screens 129 filers detritusand other trash from passing water. Screens 129 are self-cleaning due tothe high water velocities encountered when the shower valve is runninghot water.

Example 2 Single Handle Faucets w/ Bypass Valve in Moveable Valving

This family of valves may utilize either a moveable perforated hollowspherical ball 64, as shown in FIGS. 3 and 4, or an internally moveablevalve cartridge, that have a common internal flow area to selectivelyand adjustably connect the hot 20 and cold 16 lines to the dischargespout 70. It is possible to place the same thermal valve system 36 (in amore compact form) inside of a replacement one inch diameter ball 134for the moveable ball type or inside the replaceable faucet cartridgeswith internally moveable valving parts.

The previous simple hollow sphere, now 134 (shown in FIGS. 12, 13 and14), is structurally divided into two separate compartments inside ballbody 135, an outer annular compartment 136, coaxial with the centerlineof the actuating stem 138, and a cylindrical inner compartment 140, alsocoaxial with the centerline of the actuating stem 138. Passage 162,connected to annulus 159, and passage 164, connected to central bore157, are separated by the valving action of the bypass valve 36installed in compartment 140. Ball 134 is made in two parts, an upperhalf 142 and a lower half 144 (relative to the stem 138 which normallyextends upward), which screw together for convenience in developmentwork. The thermal actuator 88 is enclosed in the inner compartment 140is the same as the actuator discussed above, but with a shortened guidelength and a cut-off piston 44 with no poppet. The radially squeezedO-ring 146 seals the two halves 142 and 144 of ball 134, and is held inplace by the spring 148, which also functions as the bias or returnspring. The piston 44 is cut off short to conserve space, and bears onthe upper end of drilled hole 150. Unlike the above-mentioned actuators,this piston 44 remains stationary and it's the thermal actuator body 48that moves against spring 148 to push the elastomer poppet disc 152,which doubles as a check valve, against the stationary seat 154 as thevalve 134 heats up.

The two inlet ports on ball body 135, shown as 156 for the hot waterinlet port and 158 for the cold water inlet port on FIGS. 13 and 14,selectively and adjustably communicate with the hot 20 and cold 16lines. The ball discharge port 160 communicates in all ball positionswith the faucet spout to discharge water from faucet Ports 156, 158 and160 are located in exactly the same locations on the ball body 135 asthe prior art ball 64 previously. However all three ports are connectedwithin the ball to annular compartment 136 instead of to the entireinner volume of the hollow prior art ball 64. In the shut-off mode, thehot and cold inlet ball ports 156 and 158, respectively, of ball 134 areshifted away from the hot 20 and cold 16 lines, as with prior art ball64. However, ball 134 includes two added small ports 162 and 164 to theunperforated spherical surface that previously blocked off the hot 20and cold 16 lines. Ports 162 and 164 connect the hot 20 and cold 16lines to the central bore 157 and annulus 159, which are valved byaction of poppet disc 152. When the ball 134 is cold due to a cooled-offhot water line 20, the bypass valve. 36 opens, allowing communicationbetween the annulus 159 and central bore 157. With the faucet 10 in theshut-off position, the two added ports 162 and 164 thus allowcommunication between a cooled-Off “hot” line 20 and the cold line 16,and consequently a flow of water from the boosted “hot” line 20 to thecold line 16. Positioning slot 165 in ball 134, also in ball 64, is usedto position ball 134 in the faucet. The bypass action described above isaccomplished without change to any part of the faucet 10 except thereplaceable valving ball 134. It is thus very easy to retrofit anexisting faucet to the bypass function by simply replacing the existing“standard” design hollow ball 64 with the new ball 134, as described.

There are several major advantages to this arrangement. These advantagesinclude: (1) the complete ball 134 is easily replaced to fix amalfunctioning bypass valve 36; (2) for retrofit, the original ball 64can be removed and replaced with the new valve-in-ball 134. No otherchanges need be made to the existing faucet 10 (however, a booster pump26 located near the hot water heater 18 in the hot water line 20 does ofcourse need to be installed). This is particularly advantageous where itwould be very difficult or impractical to replace an existing completefaucet valve, such as a shower valve installed behind a tiled wall.

While the hollow ball 64 of the Delta faucet (and other clone faucets)provides an adequate space in a convenient location for installation ofthe bypass valve 36, a miniaturized version of the bypass valve 36 canalso be fitted into the replaceable cylindrical valving cartridges ofother brands of single handle faucets with an action characterized byoscillating movement about a vertical centerline to adjust watertemperature. Such a valving action to control mixing is commonly used inPrice-Pfister, Sterling, American Standard, Moen, and Kohler faucets,among others. These faucets use a push-pull or tipping lever action tooperate the on-off function within the same (usually) cylindricalcartridge. On some configurations, it is likely that space would have tobe made by lengthening these cylindrical faucet cartridges, which wouldin turn call for a compensating change to the faucet central housing.

FIG. 15 shows a modification of a widely used Moen designed faucet 200as an example of a fixture that utilizes a replaceable cylindricalvalving cartridge 202. The modifications to the faucet 200 includeadding a hot water bypass valve 36 within the moving valving spool 204of the Moen design. This valve design is of the type wherein on/off andmetering adjustment is accomplished by axial motion of the center spool204 (off is all the way inward). Hot/cold mixing adjustment is byangular positioning of the center spool 204 when it is wholly orpartially pulled out to the on position. The faucet 200 typically has abrass housing 206 connected to the cold water inlet 208 and hot waterinlet 210. A spout connection 212 allows water to exit the fixture 200.FIG. 15 shows the spool 204 in its outward or “full on” position (slot214 axially aligns with spout port 212 and slot 216 axially aligns withcold 208 and hot 210 inlet ports) and angularly rotated so that the hotport 210 is open to slot 216 but cold port 208 is blocked off.

In the position shown in FIG. 15, hot water from port 210 can enterthrough slot 216 to the interior of tubular spool 204 and proceedthrough hollow shuffle 218 to slot 214 and exit out spout port 212.Arrows 220 indicate the length of travel of the spool 204. Tubularmember 222 is a stationary (preexisting) sleeve incorporated within thehousing 206 to allow placement and retention of the three elastomerseals 224 to bear against and dynamically seal with spool 204. It alsoprovides a vent path around its exterior for the space at the “bottom”of the valve 200 to allow axial (piston) motion of spool 204 withoutencountering hydraulic lock. Spool 204 is shown in a simplifiedone-piece configuration for clarity.

The bypass valve 36 components (consisting of bias spring 226, shuttle218, actuator piston 228 and actuator 230) are enclosed within thetubular portion of spool 204. Shuffle 218 is located (floats) betweenbias spring 226 and actuator 230. Shuffle 218 has a central cruciformshaped member with an integral elastomer sleeve 232 attached to the fourlegs of the cruciform. Four axial passages within the sleeve 232 andaround the cruciform are thus provided. This elastomer sleeve 232 is incontact with and seals against the inner surface of tubular spool 204.When thermal actuator 230 is heated to its actuation temperature, it“suddenly” extends piston 228 outward, moving shuttle 218 (to the leftin FIG. 15) against bias spring 226.

Two bleed holes 234 and 236 are so located through the wall of tubularspool 204 as to line up with hot water inlet 210 and cold water inlet208, respectively, when the manually operated spool 204 is pushed allthe way into housing 206 (the off position). Further, bleed hole 236 isaxially located slightly closer to the bias spring end of spool 204.O-rings 238 seal spool 204 and retaining clip 240 holds sleeve 222within housing 206.

In FIG. 15, the bypass valve 36 components are shown in their “cold”positions. Hot bleed hole 234 is covered by the end of the elastomersleeve 232 on shuttle 218, but cold bleed hole 236 is uncovered. Withspool 204 pushed all the way in (off position) bleed hole 234communicates with hot water inlet 210 and boosted hot water pressurecommunicates through hot bleed hole 234. this pressure deflectselastomer sleeve 232 inward locally to allow flow from the boosted hotwater line 20 (presumably cooled off from a period of disuse) into theinterior of tubular spool 204 and out through uncovered cold bleed hole236, which by virtue of the spool 204 being in the off position is incommunication with cold water inlet 208. A bypass of cooled off waterfrom the hot water line 20 to the cold water line 16 is thusaccomplished.

When sufficient cooled off water has passed through the valve 200 tobring “hot” water to and through the valve 200, actuator 230 will bewarmed to its actuation temperature and will expand, forcing shuffle 218against bias spring 226. This axial movement will result in elastomersleeve 232 covering cold bleed hole 236. Boosted hot water pressureinternal to sleeve 232 will hold sleeve 232 outward against the innerwall of tubular spool 204, effectively sealing bleed hole 236, andstopping the bypass flow until the valve cools down, causing bias spring226 to force shuttle 218 back against piston 10 into contractingactuator 230, again opening cold bleed hole 236.

The elastomer sleeve 232 has a second function, that of acting as acheck valve. When any faucet in the plumbing system Is opened, theresulting flow may induce a substantial pressure drop in the associatedplumbing line (either hot 20 or cold 16, depending on which faucet wasopened). If a bypass valve 36 is open at such a time, such a pressuredifference may cause sufficient water to leak through so as toconstitute a nuisance. If the lowered pressure is on the hot water line20, no “leak” will occur as the higher pressure of the cold water insidethe sleeve 232 will hold it against the inner wall of tubular spool 204in the vicinity of hot bleed hole 234, effecting a seal. If the loweredpressure is on the cold side, the valve 200 will allow cooled off waterfrom the hot water line 20 to bypass into the cold water line until warmwater arrives at the valve 200, at which time the shuttle 218 will shiftand cut off the bypass.

Example 3 Dual Handle, Single Spout Faucets

Although two handle, single spout faucets might have been expected tofade out of demand in favor of the more convenient single handlefaucets, the two handle faucets (shown as 10 in FIG. 1) seem moreamenable to elegant cosmetic design than their single handle cousins,which have an inherently more utilitarian look. Apparently for thisreason, most double handle faucets on display are for lavatory use. Thesame requirements for ease of maintenance by allowing access to thebypass valve 36 from the top apply to this faucet type. It is convenientthat the prior art faucet design utilizing a rotating threaded stem witha faucet washer and a hard seat has become a thing of the past, as thenewer designs with replaceable cartridges are more adaptable to thismodification.

Most modern two handle faucets utilize a cartridge design in a pair ofvalve member 166, shown in FIG. 16, wherein the valving function isaccomplished within the cartridge that is positioned inside the housingsection 168 of valve member 166. This allows complete re-conditioning ofthe faucet by simply replacing a single assembly on each side. Thesecartridges are accessible in the housing section 168 from the top byremoving the faucet handles and bonnets that attach to the upperthreaded portion 170. The cartridge assembly then simply lifts out,exposing its open cavity inside housing section 168, with a side port172 leading to confluence with the like port from the other side of thefaucet, which confluence flows on through the single spout of suchfaucets. Below the mentioned cavity for the faucet valving cartridgethere is an open one-half inch (typically) threaded pipe 174 for the hotor cold conduit into the faucet. This externally threaded pipe issubstantially longer than needed for valving or connection purposes toallow for overly thick lavatory counters and to get the lower end ofthese threaded pipes far enough down behind the sink for reasonableaccess by the installer. This “extra” space on the hot water side is atop accessible, hydraulically appropriate place to locate a thermalvalve cartridge similar to the type described for inclusion in oradjacent to the hot water conduit in the central housing 62 of a singlehandle faucet. Side port 175 is added to housing section 168 and a lineis run to a like port on the other, opposing faucet. Addition of athermal bypass valve 36 requires additional machining and the additionof a bypass line connecting the hot and cold lines. An existing twohandle single spout valve thus could not be retrofitted, butmodifications to the design are relatively minor and the existingreplaceable valve cartridge would fit the new design.

The major difference of concern in this matter between single handlesingle spout and two handle single spout faucet designs is that in thesingle handle central block, it is possible to create the connectingpassages (bypass) by simply drilling cross holes, as discussed above.With two separate hot and cold faucet valves located four inches apart,some kind of cross conduit for the bypass must be added. There seem tobe two approaches to directing the water from the hot and cold faucetsto a confluence and out to the single spout. American-Standard, Oasis,La Bella and some Price-Pfister's use a large brass casting thatincludes the spout, both hot and cold faucet housings, and a cored castpassage connecting all of this together. Adding a thermal bypass valve36 to such a two handle faucet set would require the addition of anadditional cored cast passage to accomplish the bypass function betweenhot and cold lines. Delta, Moen, Kohler, and some Price Pfister twohandle single spout valves use brazed-in copper tube manifolds insteadof cored cast passages. These would require the addition of a tubularcross passage brazed in. The Delta two handle single spout valve has asomewhat different valving action which makes it much more difficult tofit in a thermal valve cartridge. This new passage (cored or brazedtubular) needs to connect to the vertical hot and cold “pipe” membersbelow their existing side port to the spout. These faucet sets generallydo not have sufficient vertical space under the polished bezel toaccommodate the extra passage. This will require addition of somevertical length to the skirt of the valve bezel.

FIG. 17 shows a modified “hot” side of a Kohler two handle faucet 176,with the housing shown as 178. The housing 178 is identical to thestandard existing Kohler housing 178 above (to the right of) line AA.The housing 178 must be bored out in several steps to accommodate thenew thermal valve cartridge 180, which can be a molded plastic cartridgeidentical in function to that already described for the center block ofthe Delta single handle valve, It varies from the previously describedcartridge in the configuration of the passage to bring the hot waterpast the thermal valve 36 to the faucet, and the configuration of thesnap fit for the thermal actuator 88. It also has an upper extension 182with a through hole 184. The extension 182 fits into a recess in thebottom of the existing Kohler faucet cartridge and the through hole 184is for engagement of a hook to allow removal of the thermal valvecartridge 180 for replacement of the thermal bypass valve 36.

The operation of the bypass valve 36 inside of faucet 10 of the presentinvention is summarized on the chart shown as FIG. 18 which indicatesthe results of the twenty combinations of conditions (pump on/pump off;hot water line hot/hot water line cooled off; hot faucet on, or off, orbetween; cold faucet on or off, or between) that are applicable to theoperation of valve 36. The operating modes IVB, IVC, IVD, IIIB, & IIIDare summarized detailed in the immediately following text The operationof the remaining fifteen modes are relatively more obvious, and may beunderstood from the abbreviated indications in the outline summarizingFIG. 18. Starting with the set “off hours (normal sleeping time, anddaytime when no one is usually at home) pump 26 will not be powered.Everything will be just as if there were no pump 26 and no bypass valve36 installed in faucet 10 (i.e., both the cold and hot water lines willbe at the same city water pressure). The hot water line 20 arid bypassvalve 36 will have cooled off during the long interim since the last useof hot water. The reduced temperature in the valve results in“retraction” of rod member 40 of the thermally sensitive actuator 88.The force of bias spring 106 pushing against flange 46 on rod member 40will push it back away from valve seat 90, opening valve 36 forrecirculation. Although the thermal actuating element 88 is open, withpump 26 not running, no circulation flow results, as the hot 20 and cold16 water piping systems are at the same pressure. This is the modeindicated as IVB in the outline on FIG. 18. If the cold water valve atfaucet 10 is opened with the thermal element 88 open as in mode IVBabove, pressure in the line 16 to the cold water side of faucet 10 willdrop below the pressure in the hot water line 20. This differentialpressure will siphon tepid water away from the hot side to the coldside, which is the mode indicated as IVD in the outline on FIG. 18. Therecirculation of the “hot” water will end when the tepid water isexhausted from the hot water line 20 and the rising temperature of theincoming “hot” water causes the thermal element 88 to close.

If the hot water valve is turned on with the thermal element 88 open asin mode IVB above, pressure in the line 20 to the hot water side offaucet 10 will drop below the pressure in the cold water line 16. Thisdifferential pressure, higher on the cold side, will load check valve 96in the “closed” direction allowing no cross flow. This is mode IVC inthe outline on FIG. 18. In this mode, with the hot water line 20 cooledand the pump off, a good deal of cooled-off water will have to be runjust as if valve 36 were not installed), to get hot water, at which timethe thermal element 88 will close without effect, and without notice bythe user. With the thermal element 88 open and the hot water line 20cooled-off as in mode IVB above, at the preset time of day (or when thecyclic timer trips the next “on” cycle) the pump 26 turns on,pressurizing the water in the hot side of faucet 10. Pump pressure onthe hot side of faucet 10 results in flow through the open thermalelement 88, thereby pressurizing and deflecting the check valve 96poppet away from its seat to an open position. Cooled-off water at theboosted pressure will thus circulate from the hot line 20 through thethermal element 88 and check valve 96 to the lower pressure cold line 16and back to water heater 18.

This is the primary “working mode” of the bypass valve 36 and is themode indicated as IIIb in the outline on FIG. 18. If the cold watervalve is turned on during the conditions indicated in mode IIIB above(i.e., pump 26 operating, hot line 20 cooled off, the hot valve atfaucet 100 ff) and while the desired recirculation is occurring, modeIIID will occur. A pressure drop in the cold water line 16 due to coldwater flow creates a pressure differential across valve 36 in additionto the differential created by pump 26. This allows tepid water to morerapidly bypass to the cold water inlet 22 at faucet 10. When the tepidwater is exhausted from the hot water line 20, thermal element 88 willclose, ending recirculation,

Explanation of FIG. 18 Table

-   MODE Water In Hot Water Supply Line Hot, Pump On.    -   A. Hot and cold faucet valves full open        -   Pressure drops from hot and cold flow about equal. Actuator            element 26 stays closed. No leak or recirculation in either            direction.    -   B. Hot and cold faucet valves fully closed        -   Thermal actuator 88 keeps valve 36 closed. No recirculation.    -   C. Hot faucet valve fully open, cold faucet valve closed        -   Actuator element 88 closed. Check valve 96 closed, No            recirculation. No leak.    -   D. Hot faucet valve closed, cold faucet valve fully open        -   Actuator element 88 closed. No recirculation. No leak.    -   E. Hot and cold faucet valves both partially open in any        combination        -   Actuator element 88 closed. No recirculation. No leak.-   MODE II: Water in Hot Water Supply Line Hot, Pump Off.    -   A. Hot and cold faucet valves full on        -   Pressure drops from hot and cold flow about equal. Actuator            element 88 stays closed.    -   B. Hot and cold faucet valves fully closed        -   Thermal actuator 88 keeps valve 36 closed. No recirculation.    -   C. Hot faucet valve fully open, cold faucet valve closed        -   Thermal actuator 88 closed. Check valve 96 closed. No            recirculation. No leak.    -   D. Hot faucet closed, cold faucet fully open        -   Thermal actuator 88 closed. No recirculation. No leak.    -   E. Hot and cold faucets both partially open in any combo        -   Thermal actuator 88 closed. No recirculation. No leak.-   MODE III: Water in Hot Water Line Cooled Off, Pump On.    -   A. Hot and cold faucet valves full open        -   Flow-induced pressure drops about equal, valve 36 stays open            and allows recirculation hot to cold until tepid water is            exhausted and hotter water closes thermal actuator 88. If            both faucet valves are at same sink, they are mixing hot and            cold anyway. If faucet valves being manipulated are at            remote sinks on the same plumbing branch, this short time            tepid-to-cold leak will probably not be noticeable. If            faucet valves being manipulated are on remote branches of            plumbing, the mixing would have no effect.    -   B. Hot and cold faucet valves fully closed        -   Thermal actuator 88 open, get desired tepid-to-cold            recirculation until hot line heats up.    -   C. Hot faucet valve fully open, cold faucet valve closed        -   Thermal actuator 88 open but pressure drop in hot line may            negate pump pressure, stopping recirculation. Check valve 96            stops cold to hot leak.    -   D. Hot faucet valve closed, cold faucet valve fully open        -   Thermal actuator 88 open, get tepid to cold recirculation            until hot line heats up.    -   E. Hot and cold faucets both partially open in any combination        -   Could get tepid to cold leak. If faucet valves at same sink            don't care as mixing hot and cold anyway. If at remote sinks            probably not noticeable. Tepid to cold leak would be short            term.-   MODE IV: Water In Hot Water Supply Line Cooled Off, Pump Off.    -   A. Hot and cold faucet valves full open        -   Flow-induced pressure drops about equal, valve 36 stays open            and may allow recirculation (leak) hot to cold until tepid            water is exhausted and hotter water closes thermal actuator            88. Don't care, if both faucets are at same sink as are            mixing hot and cold anyway. If faucet valves being            manipulated are at remote sinks on the same plumbing branch,            this short time tepid-to-cold leak would probably not be            noticeable. If faucets being manipulated are on remote            branches of plumbing, mixing would not be noticeable.    -   B. Hot and cold faucet valves fully closed        -   Thermal actuator 88 open, no recirculation.    -   C. Hot faucet valve fully open, cold faucet valve fully closed        -   Thermal actuator 88 open. Check valve 96 closed. No leak    -   D. Hot faucet valve closed. Cold faucet valve fully open        -   Valve 36 open, tepid to cold recirculation until thermal            actuator 88 heats up and closes.    -   E. Hot and cold faucet valves both partially open, in any combo        -   Could get tepid to cold leak, If faucet valves at same sink,            don't care as mixing hot and cold anyway. If at remote sinks            probably not noticeable. Tepid to cold leak would be short            term.

Several further enhancements have been developed for the thermal valveactuator 88, which are applicable to all of the above-described faucetsare shown in FIG. 19. It has been noted that “lime” or “calcium”buildups on the piston 44 can cause sticking of the piston 44 in theactuator 88. Manufacturers of these thermal actuators 88 recommend useof an elastomer boot or a nickle-teflon coating on the piston 44, or useof a plastic piston 44. A preferred material may be use of a plasticpiston 44, to which the buildup could not get a tenacious hold, and theremoval of the internal chamfer at the open end of guide bore 186 andreplacement with a sharp corner 188, as shown in FIG. 19. Removal of thechamfer and replacement with corner 188 would provide a sharper scrapingedge to clean the piston 44, and would eliminate a place where thedetritus could become wedged. In addition to the chamfer removal,another simple geometry change to the piston 44 might be very effective.As shown in FIG. 19, a long shallow groove 190 in or a reduced diameterof piston 44 that would extend from just inside the guide bore 186 (atfull extension) to just outside the guide bore 186 at full retractionwould provide a recess to contain buildup for a long period. Once thisrecessed area filled up with lime, the edge 188 of guide bore 186 couldscrape off the incrementally radially extending soft build up relativelyeasily, as compared to scraping off the surface layer that bonds moretenaciously to the metal.

The most direct method to overcome sticking due to mineral buildup is tooptimize actuator force in both directions. Buildup of precipitatedminerals on the exposed outside diameter of the extended piston 44 tendsto prevent retraction, requiring a strong bias spring 106. This highbias spring force subtracts from the available extending force however,thereby limiting the force available to both extend the piston 44against the mineral sticking resistance and to effect an axial sealbetween poppet and seat.

When water temperature is high, the piston 44 is extended so that itssurface is exposed. Deposition also occurs primarily at hightemperatures, so that buildup occurs on the piston outside diameter,resulting in sticking in the extended position when the growth on thepiston outside diameter exceeds the guide 186 interior diameter.Significantly more than half of the available actuator force thus canmost effectively be used to compress the bias spring 106, resulting in amaximum return force.

While there is shown and described herein certain specific alternativeforms of the invention, it will be readily apparent to those skilled inthe art that the invention is not so limited, but is susceptible tovarious modifications and rearrangements in design and materials withoutdeparting from the spirit and scope of the invention. In particular, itshould be noted that the present invention is subject to modificationwith regard to the dimensional relationships set forth herein andmodifications in assembly, materials, size, shape, and use.

FIG. 20 is a side elevation view showing a water circulation system 1067and fixture 1080 utilizing a bypass valve 1010 in accordance with anexemplary embodiment. In order to achieve the desired circulation flow,a single circulating pump 1066 is utilized as part of the watercirculating system 1067. Pump 1066 can be a single, small pump of thetype used in residential hot water space heating. To avoid reduced flow,a check valve 1070 can be plumbed in parallel with pump 1066 orincorporated within the pump housing, to pass a flow rate exceeding thepump's capacity around pump 1066. When pump 1066 is powered and flowdemand is low, check valve 1070 prevents the boosted flow fromre-circulating back to its own inlet. With check valve 1070 plumbedaround pump 1066, it is advantageous to place an orifice 1072 in thepump discharge to provide a simple manner to achieve the desired verysteep flow-head curve from available stock pump designs. A single pump1066 located at or near the water heater 1068 in its discharge pipingwill boost the pressure in the hot water pipes somewhat above that inthe cold water pipes (i.e., perhaps one to three feet of boost). Withthis arrangement only one pump 1066 per plumbing system (i.e., per waterheater) is required with any reasonable number of remote faucet sets(i.e., the typical number used in residences) equipped with bypassvalves 1010. This is in contrast to those systems that require multiplepumps, such as a pump at each fixture where bypassing is desired.

In one embodiment, pump 1066 may operate twenty-four hours a day, withmost of the time in the no flow mode. However, this is unnecessary andwasteful of electricity. Alternatively, pump 1066 can have a timer 1074to turn on the pump 1066 daily at one or more times during the day justbefore these occasions when hot water is usually needed the most (forinstance for morning showers, evening cooking, etc.) and be set tooperate continuously for the period during which hot water is usuallydesired. This still could be unnecessary and wasteful of electricity.Another alternative is to have the timer 1074 cycle pump 1066 on and offregularly during the period when hot water is in most demand. The “on”cycles should be of sufficient duration to bring hot water to all remotefixtures that are equipped with a bypass valve 1010, and the “off”period would be set to approximate the usual time it takes the water inthe lines to cool-down to minimum acceptable temperature. By using atime-of-day control timer 1074, pump 1066 operates to maintain “instanthot water” only during periods of the day when it is commonly desired.During the off-cycle times, the plumbing system operates just as if thebypass valves 1010 and pump 1066 were not in place. This saveselectrical power usage from pump operation and, more importantly, avoidsthe periodic introduction of hot water into relatively uninsulated pipesduring the off-hours, thereby saving the cost of repeatedly reheatingthis water. The time-of-day control also avoids considerable wear andtear on pump 1066 and the bypass valves 1010. Considerable additionalbenefits are gained by using a cyclic timer 1074, with or without thetime-of-day control.

Optionally, a switch 1076 may be provided within the water circulationsystem 1067 to detect flow characteristics of water within the watercirculation system 1067, such as in the supply pipes. The switch 1076may be used with or without the timer 1074 to control the operation ofthe pump 1066. The switch 1076 may be located at the pump 1066 or theswitch 1076 may be located elsewhere in the system, such as at thefixture, at the cold water pipe, at the hot water pipe, at the waterheater, and the like. The switch may be sized to detect significantflows only (e.g., those flows that are much larger than the bypass valve1010 flows), such as a shower flowing. Optionally, the switch 1076 mayconstitute a flow sensor that operates to detect a flow characteristicof actual flow of water through the pipes. Alternatively, the switch1076 may constitute a pressure sensor that operates to detect a flowcharacteristic of either a pressure value at a particular point withinthe water circulation system 1067, or a change in pressure within thewater circulation system to detect flow. Alternatively, the switch 1076may constitute a temperature sensor that operates to detect a flowcharacteristic of temperature, such as a change in temperature to detectflow of water through the water circulation system 1067. Alternatively,the switch 1076 may constitute a manually activated switch, a motiondetector, a photo-detector, a noise detector, an infrared sensor, or anappliance activation sensor for activating the pump 1066. When a cyclictimer 1074 is used, the switch 1076 may be wired in series with the pumpmotor, and the switch 1076 may prevent the motor from starting if anexisting flow is detected at the moment the timer calls for pump on. Theuse of such a switch 1076 accomplishes several useful objectives,including reducing electrical power usage and extending pump life if hotwater is already flowing and there is no need for the pump to operate,avoiding a sudden temperature rise and the likelihood of scalding thatcould result from the pump boost if water is being drawn from a “mixing”valve (such as a shower or single handle faucet) and allowing use of a“large” pump (now that the danger of scalding is eliminated) with itsdesirable low pressure drop at high faucet flows, thereby eliminatingthe need for the parallel check valve 1070 required with a “small” pump.

In alternative embodiments, the water circulation system 1067 may alsoinclude at least one temperature sensor 1075 coupled to the pipes of thewater circulation system for providing temperature feedback to the pump1066. The operation of the pump 1066 may be controlled by thetemperature sensor 1075, such as by turning the pump 1066 on when thetemperature of the water reaches a predetermined threshold, oralternatively, falls by a predetermined amount or at a predeterminedrate. Similarly, the pump may be turned off when the temperature of thewater reaches a predetermined threshold, or alternatively, rises by apredetermined amount or at a predetermined rate. In another alternativeembodiment, the pump 1066 may be controlled based on the flow of waterwithin the water circulation system 1067. For example, by using theswitch 1076 as a flow detector (e.g. a flow sensor, a pressure sensor, atemperature sensor, and the like), the operation of the pump 1066 may becontrolled based on flow characteristics of the water in the watercirculation system 1067. Alternatively, the switch 1076 may be locatedat another position within the water circulation system 1067, such asremote from the pump 1066.

Installation of the bypass valve 1010 may be made easy by manufacturingthe valve 1010 with a single piece valve body having four ports to allowinstallation with commonly used under-sink (as an example) vinyl hosesor flexible metal pipe, shown as 1078 in FIG. 20, having swivel ends andfaucet washers. The inlet ports may be formed with one-half inchstraight pipe threads to allow the installer to remove the end of thewall shut off-to-faucet hoses (hot and cold) at the faucet 1080 andconnect those ends, which are commonly one-half inch straight pipethreads, to inlets of the bypass valve 1010. Discharge ports of thebypass valve 1010 may be similarly molded with one-half inch straightpipe threads to allow connection from them to the hot 1082 and cold 1084inlets at faucet 1080. The threads on all four ports will seal with hosewashers and swivel nuts. Because the use of a plastic valve body isenvisioned, the inability to mount valve body directly to “hard”plumbing with taper pipe threads insures that the body will be connectedonly with flexible lines 1078, thereby precluding any plumbing loadsthat might overstress the non-metallic body. Because all currentAmerican faucets 1080 are equipped with one-half inch straight pipethreads, the recommended procedure is to remove the pair of existingconnection hoses 1078 from the faucet 1080 and connect these loose endsto the appropriate inlet ports of valve body. The angle stop valves atthe wall may have any of several possible thread size connections, ormay have permanently connected hoses or tubes. As a result, it is bestnot to disturb these wall connections, but instead use hoses 1078 toconnect from the angle stop to bypass valve 1010. A new set of hoses1078 with one-half inch straight pipe thread swivel nuts at both endscan then be connected from discharge ports 1020 and 1024 of valve body1012 to the appropriate hot 1082 and cold 1084 water connections onfaucet 1080. Other interconnection methods may also be sued tointerconnect the bypass valve 1010 with the hot and cold supply linesand the fixture 1080.

FIG. 21 is a side elevation view of the bypass valve 1010 in a firststate with a portion of a body 1012 of the bypass valve 1010 cutaway toillustrate the various components of the bypass valve 1010. The bypassvalve 1010 is illustrated in a first or closed state in which water isrestricted from flowing through the bypass valve 1010, as will bedescribed in more detail below. Bypass valve 1010 includes the valvebody 1012, which is generally tubular and includes a first end 1014, asecond end 1016 and a separating wall 1017 disposed between first end1014 and second end 1016. First end 1014 is designated to receive anddischarge hot water and second end 1016 is designated to receive anddischarge cold water from a source of cold water, such as a city watersupply system or a local water well. Tubular valve body 1012 has fourthreaded ports, an axial and radial port at the first end 1014 and anaxial and radial port at the second end 1016. For purposes of discussionherein, the axial ports are designated as inlet ports and the radialports are designated as discharge ports, however, the inlet ports may bethe radial ports and the discharge ports may be the axial ports, or theinlet and discharge ports may be any combination of axial and/or radialports. In one embodiment, the bypass valve 1010 is integrated with apump, such as the pump 1066 described above, and the integratedpump/bypass valve unit is provided in the circulation system 1067, suchas at a position proximate the fixture 1080.

At the first end 1014 (the hot water side) is first inlet port 1018 andfirst discharge port 1020 and at the second end 1016 (the cold waterside) is second inlet port 1022 and second discharge port 1024. Thefirst 1018 and second 1022 inlet ports connect to the hot and cold waterdistribution system and first 1020 and second 1024 discharge portsconnect to the hot and cold water valves on the fixture (e.g., sink,shower, bathtub, appliance, and the like) with which the bypass valve1010 is utilized.

Valve body 1012 houses a thermally sensitive actuating element 1026, abias spring 1028, an over-travel spring 1030, multiple screens 1032,multiple retaining pins 1034 and a check valve 1036. Valve body 1012 canmost economically and effectively be manufactured out of a moldedplastic material, such as Ryton, a polyphenylene sulphide resinavailable from Phillips Chemical, or a variety of composites. Moldedplastic materials are preferred due to their relatively high strengthand chemical/corrosion resistant characteristics while providing theability to manufacture the valve body 1012 utilizing injection moldingprocesses with the design based on the configuration described hereinwithout the need for expensive casting or machining. Alternatively,valve body 1012 can be manufactured from various plastics, reinforcedplastics or metals that are suitable for “soft” plumbing loads andresistant to hot chlorinated water under pressure. Valve body 1012 ismolded with wall 1017 having a passage 1037 therein interconnectingfirst end 1014 and second end 1016 to allow fluid to flow therethrough,an internal shoulder 1040 inside valve body 1012 at an end of passage1037 for fixedly receiving and positioning one end of the bias spring1028, an internal shoulder 1041 inside valve body 1012 for fixedlyreceiving and positioning one end of the over-travel spring 1030, andretaining pin holes 1044 for receiving retaining pins 1034. First end1014 is molded with retaining slot 1046 for engagement with the checkvalve 1036 and one of the retaining pins 1034 is used to hold the cheekvalve 1036 in place. The valve body 1012 is designed so the componentscan fit through either of the inlet and/or discharge ports, which willtypically be one-half inch diameter. In this manner, a single unitbypass valve 1010 results with no intermediate or additional jointsrequired for installation.

Optionally, thermally sensitive actuating element 1026 may be of the waxfilled cartridge type, also referred to as wax motors, having a mainbody 1054 with a portion surrounded by a casing 1055 and an integralpiston/poppet rod member 1050 extending from the main body 1054. Rodmember 1050 comprises poppet 1051 attached to piston 1052 with anintermediate flange 1053 thereon. The end of poppet 1051 may seatagainst a valve seat 1042 to close passage 1037. Piston 1052 extendsbeyond the end of poppet 1051 through passage 1037 and into check valve1036. Piston 1052 interacts with a stopper or ball 1035 housed withincheck valve 1036 as described in further detail below. Alternatively,rather than piston 1052 extending into check valve 1036, piston 1052 mayend at a cold side of poppet 1051 and an extension arm may extend from ahot side of poppet 1051 through passage 1037 and into check valve 1036.The body 1054 of actuating element 1026 has a section 1056 of increaseddiameter to seat against shoulder 1041 in valve body 1012. Over-travelspring 1030 abuts against first side 1058 of actuator body 1054 andsecond side 1060 of actuator body abuts against shoulder 1041. Piston1052 of rod member 1050 interconnects poppet 1051 with actuator body1054.

Actuating element 1026 operates based on temperature. For example,Actuating element 1026 comprises a wax or a mixture of wax and metalpowder (e.g., copper powder) enclosed in actuator body 1054 by means ofa membrane made of elastomer or the like. Upon heating the wax or waxwith copper powder mixture slowly expands, thereby pushing piston 1052and poppet 1051 of rod member 1050 in an outward direction. Uponcooling, the wax or wax/copper powder mixture contracts and rod member1050 is pushed inward by bias spring 1028 until flange 1053 contactscasing 1055 at actuator seat 1064, which is described in more detailbelow. Although other types of thermal actuators, such as bimetallicsprings and memory alloys (e.g. Nitinol and the like) can be utilized,the wax filled cartridge type is illustrated in FIG. 21 because the waxcan be formulated to change from the solidus to the liquid state at aparticular desired temperature. The rate of expansion with respect totemperature at this change of state is many times higher, resulting inalmost snap action of the wax actuating element 1026. The temperatureset point is equal to a preset value, such as 97 degrees Fahrenheit,desired for the hot water. This is a “sudden” large physical motion overa small temperature change. As stated above, this movement is reacted bybias spring 1028, which returns rod member 1050 as the temperaturefalls.

Also inside valve body 1012 is an over-travel spring 1030, disposedbetween the first side 1058 of the actuator body 1054 and one of theretaining pins 1034 located inside valve body 1012 to prevent damage toa fully restrained actuator 1026 heated above the bypass valve's 1010maximum operating temperature and to hold the actuator 1026 in placeduring operation without concern for normal tolerance. Over-travelspring 1030 allows movement of the actuator body 1054 away from theshoulder 1041 in the event that temperature rises substantially. Withoutthis relief, the expanding wax would distort the casing 1055, destroyingthe calibrated set point. The over-travel spring 1030 also holds thebias spring 1028, rod member 1050 and actuator body 1054 in placewithout the need to adjust for the stack-up of axial tolerances.Alternatively, actuator 1026 can be fixedly placed inside valve body1012 by various mechanisms known in the art, including adhesives and thelike. Over-travel spring 1030 can be held in place by various internalconfigurations commonly known in the art, such as a molded seat. In thepreferred embodiment, however, over-travel spring 1030 abuts againstscreen 1032, which is held in place by cantilevered retention pin 1034.Screen 1032 can be a small wire fabric, mesh-type screen that is shapedand configured to fit within the first end 1014 of valve body 1012.Screen 1032 is utilized to keep hard water lime particles and otherdetritus out of bypass valve 1010 and to act as a seat for theover-travel spring (as explained above).

The check valve 1036 includes a check valve body 1061 having an inlet1062 and an outlet 1063. The inlet 1062 is positioned on the hot side ofthe check valve 1036 (e.g. the side facing and communicating with thehot water inlet) and the outlet 1063 is positioned on the cold side ofthe check valve 1036 (e.g. the side facing and communicating with thecold water inlet). Optionally, the outlet 1063 may be approximately thesame size as the inlet 1062. Alternatively, the body may include an openend that defines the outlet 1063, but the open end is positionedadjacent the passage 1037. The stopper 1035 is positioned within thebody 1061 between the inlet 1062 and the outlet 1063. The stopper 1035is movable within the body 1061 to stop water flow therethrough based ona position of the stopper 1035 with respect to the inlet 1062 and theoutlet 1063. The stopper 1035 is sized and shaped to fill or cover theopenings defining the inlet 1062 or outlet 1063 to restrict water flowtherethrough. As indicated above, a portion of the actuating element1026 is received within the check valve 1036 for positioning the stopper1035. In the illustrated embodiment, a portion of the piston 1052extends into the check valve 1036 and holds the stopper against theinlet 1062. The stopper 1035 is illustrated in a closed position,wherein the stopper 1035 blocks water flow through the inlet 1062, aswill be described in further detail below. When the piston 1052 is movedaway, the stopper 1035 is free to move to a neutral position whereinwater can flow through the inlet 1062 and into the outlet 1063. When theactuating element 1026 is in a failed state, as explained below, thestopper 1035 is able to block the outlet 1063 and prevent water flowthrough the outlet 1063. Optionally, the check valve 1036 may includeguides for guiding the stopper 1035 along a predetermined path, such asa linear path.

In operation, the actuating element 1026 is operable in three states,namely an open state, a closed state, and a failed state. The actuatingelement 1026 transitions between the open and closed states based on atemperature of the water at the bypass valve 1010. For example, the bodyof the actuating element 1026 expands and contracts based ontemperature. As indicated above, FIG. 21 represents the bypass valve1010 in a closed state, In the closed state, the body 1054 of theactuating element 1026 is expanded within the casing 1055, thus forcingthe rod member 1050 to move toward the first end 1014 of the valve body1012, indicated by the arrow A. A portion of the piston 1052 extendsinto the check valve 1036 and engages the stopper 1035. In the closedposition, the actuating element 1026 is actuated to an extent such thatthe piston 1052 forces the stopper 1035 to plug the inlet 1062 andrestrict flow of water through the check valve 1036. As the body 1054 ofthe thermal actuator 1026 cools, the thermal actuator 1026 will, at somepoint, contract, and the bias spring 1028 forces the rod member 1050 tomove toward the second end 1016, indicated by the arrow B. When the body1054 contracts, the piston 1052 releases the stopper from the closedposition and water will flow through the inlet 1062. This situation isdescribed in more detail with respect to FIG. 22.

FIG. 22 is a side elevation view of the bypass valve 1010 in a secondstate, wherein the bypass valve 1010 is open. In the open state, wateris allowed to flow through the check valve 1036 from the inlet 1062 tothe outlet 1063. The water then flows past the actuating element 1026and into the cold water side of the bypass valve 1010. Due to theincreased pressure of the water on the hot side, the water flows fromthe hot side to the cold side and then returns through the cold waterpipes to the water heater 1068 (shown in FIG. 20). Alternatively, aseparate return pipe may be provided to return the water to the waterheater 1068, As indicated above, the actuating element 1026 isresponsive to changes in temperature. When the temperature of the watersurrounding the actuating element 1026 is decreased, the body 1054 ofthe actuating element 1026 contracts, thus moving the rod member 1050 inthe direction of the cold side of the bypass valve 1010, indicated bythe arrow C.

Under normal operating conditions, the contraction of the body 1054moves the rod member 1050 to the open position, wherein the end of thepiston 1052 is positioned within the check valve 1036 such that water isallowed to flow through both the inlet 1062 and the outlet 1063. Forexample, the piston 1052 holds the stopper 1035 away from the outlet1063 such that the stopper 1035 is not blocking water flow through theoutlet 1063. Additionally, the piston 1052 is retracted from the closedposition, illustrated in FIG. 21, such that the piston 1052 is notholding the stopper 1035 against the inlet 1062 as described above.

When the pump 1066 (shown in FIG. 20) is operating, water is channeledfrom the hot side 1014 to the cold side 1016 via the bypass valve 1010as described above. As the cooled water is channeled through the bypassvalve 1010, the cooled water is replaced by hot water from the waterheater 1068. When the hot water reaches the actuating element 1026, thebody 1054 is heated and, based on the temperature of the body 1054,expands to the closed position, which is illustrated in FIG. 21. Thecheck valve 1036 then restricts flow of water through the bypass valve1010. The temperature of the water surrounding the actuating element1026 then begins to cool, and at a predetermined temperature, the body1054 will again contract. If the pump 1066 is still operating, thenwater from the hot side is channeled through the bypass valve 1010. Theprocess is repeated to maintain hot water at the hot side of the bypassvalve 1010. As described above, over time the range of motion of theactuating element 1026 is diminished, and eventually the actuatingelement 1026 fails, wherein the amount of expansion and contraction isnot enough to maintain the bypass valve 1010 in the closed state and/orthe open state. With prior systems, the actuating element 1026 fails inan open state, wherein water is able to flow through the bypass valve1010 at all times. This is known as bleeding. The bypass valve 1010 isdesigned to fail in a closed state, wherein flow is restricted throughthe bypass valve 1010 when the actuating element 1026 fails. The failedstate is described below with reference to FIG. 23.

FIG. 23 is a side elevation view of the bypass valve 1010 in a thirdstate, wherein the actuating element 1026 has failed and the bypassvalve 1010 is closed. This failed state is representative of thesituation in which the actuating element 1026 can no longer perform anormal operation of maintaining the bypass valve 1010 in the closedstate, as illustrated in FIG. 21, and the open state, as illustrated inFIG. 22. In the failed state, the actuating element 1026 ishyper-contracted, wherein the rod member 1050 is retracted beyond anopen position. In this hyper-contracted state, the end of the piston1052 is positioned within the passage 1037. The end of the piston 1052is contracted beyond the interface of the outlet 1063 such that thepiston 1052 no longer holds the stopper 1035 away from the openingdefining the outlet 1063. The stopper 1035 is able to plug the outlet1063 in the failed state. As such, when the pump 1066 (shown in FIG. 20)is operated and a positive head is provided to the hot side of thebypass valve 1010, the flow of the water forces the stopper 1035 to plugthe outlet 1063 of the check valve 1036. Similarly, when a negative headis provided to the hot side, such as when the fixture is demanding hotwater, the water tends to flow from the cold side of the bypass valve1010 through the check valve 1036. In this situation, the stopper 1035is forced by the flow of the water toward the inlet 1062 and the stopper1035 plugs the inlet 1062 to prevent flow from the cold side to the hotside of the bypass valve 1010. The check valve 1010 thus functions as atwo-way valve, restricting flow in both directions, when the bypassvalve 1010 is in the failed state.

FIG. 24 is a side elevation view of an alternative bypass valve 1110 foruse within the water distribution system 1067 shown in FIG. 20 with aportion of a body 1112 of the bypass valve 1110 cutaway to illustratethe various components of the bypass valve 1110. The bypass valve 1110is illustrated in a first or closed state in which water is restrictedfrom flowing through the bypass valve 1110, as will be described in moredetail below. The valve body 1112 includes a first end 1114, a secondend 1116 and a separating wall 1117 disposed between first end 1114 andsecond end 1116. First end 1114 is designated to receive and dischargehot water and second end 1116 is designated to receive and dischargecold water from a source of cold water, such as a city water supplysystem or a local water well. At the first end 1114 (the hot water side)is first inlet port 1118 and first discharge port 1120 and at the secondend 1116 (the cold water side) is second inlet port 1122 and seconddischarge port 1124. The first 1118 and second 1122 inlet ports connectto the hot and cold water distribution system and first 1120 and second1124 discharge ports connect to the hot and cold water valves on thefixture (e.g., sink, shower, bathtub, appliance, and the like) withwhich the bypass valve 1110 is utilized.

Valve body 1112 houses a thermally sensitive actuating element 1126, abias spring 1128, a check valve 1136, and a retaining cap 1138. Valvebody 1112 is molded or manufactured to have a main passage 1130 forhousing the various components of the actuating element 1136, the biasspring 1128, the check valve 1136 and the retaining cap 1138. The valvebody 1112 is also molded or manufactured to have a first or hot sideconnecting passage 1132 and a second or cold side connecting passage1134. The hot side connecting passage 1132 interconnects the first end1114 and the main passage 1130 and the cold side connecting passage 1134interconnects the second end 1116 and the main passage 1130. As such afluid path is created between the first and second sides 1114 and 1116via the passages 1130, 1132 and 1134. The main passage 1130 includes aninternal shoulder 1140 for positioning one end of the retaining cap1138. The valve body 1112 is designed so the components can fit throughan opening 1141 at an end of the main passage 1130 during manufacture orrepair of the bypass valve 1110. The retaining cap 1138 may bethreadably coupled to the valve body 1112 at the opening 1141. Theretaining cap 1138 retains the various components within the mainpassage 1130 and closes and seals the opening 1141. In the illustratedembodiment, the retaining cap 1138 includes a recess 1142 that receivesa portion of the actuating element 1126 and operates as a stop or anabutment for the actuating element 1126.

Optionally, thermally sensitive actuating element 1126 may be of the waxfilled cartridge type having a main body 1154 with a portion surroundedby a casing 1155 and an integral rod member 1150 extending from the mainbody 1154. Rod member 1150 comprises a washer 1151 attached to a piston1152. One end of the piston 1152 is received within the recess 1142 andengages the retaining cap 1138. The other end of the piston 1152 isreceived within the casing 1155. The end of the piston 1152 within thecasing 1155 is movable within the casing 1155 during actuation (e.g.expansion and contraction) of the actuation element 1126. The washer1151 allows for relative movement of the piston 1152 within the casing1155. An extension arm 1156 extends from a base 1157 of the casing 1155opposite the washer 1151. The extension arm 1156 extends into the checkvalve 1136, as explained in further detail below. The easing 1155includes a section 1158 of increased diameter defining a rim. The biasspring 1128 extends between the check valve 1136 and the section 1158.The bias spring 1128 forces the casing 1155 generally away from thecheck valve 1136.

Actuating element 1126 comprises a wax or a mixture of wax and metalpowder (e.g., copper powder) enclosed in the casing 1155. Upon heatingthe wax or wax with copper powder mixture slowly expands, therebypushing against piston 1152 and forcing the casing 1155 in an outwarddirection away from the retaining cap 1138 in the direction of the checkvalve 1136, indicated by arrow E. Upon cooling, the wax or wax/copperpowder mixture contracts and the bias spring 1128 forces the casing 1155away from the check valve 1136, indicated by arrow F. When the wax orwax/copper mixture contracts, the end of the piston 1152 is more deeplyreceived within the casing 1155 by replacing a portion of the spacepreviously taken up by the wax or wax/copper mixture. The temperature ofthe water surrounding the actuating element 1126 is transferred by thecasing 1155 to the wax or wax/copper mixture to allow the expansion andcontraction.

The check valve 1136 is similar to the check valve 1036 described withrespect to FIGS. 21-23. The check valve 1136 includes a body 1161 havingan inlet 1162 and an outlet 1163, The inlet 1162 is positioned on thehot side of the check valve 1136 (e.g. the side facing and communicatingwith the hot water inlet) and the outlet 1163 is positioned on the coldside of the check valve 1136 (e.g. the side facing and communicatingwith the cold water inlet). A stopper 1135 is received within the body1161 and is positioned between the inlet 1162 and the outlet 1163. Thestopper 1135 is movable within the body 1161 to stop water flowtherethrough based on a position of the stopper 1135 with respect to theinlet 1162 and the outlet 1163. The stopper 1135 is sized and shaped tofill or cover the openings defining the inlet 1162 or outlet 1163 torestrict water flow therethrough. As indicated above, the actuating arm1156 of the actuating element 1126 is received through the outlet 1163for positioning the stopper 1135 within the check valve 1136. Theactuating arm 1156 and the stopper 1135 are illustrated in a closedstate in FIG. 24. The actuating arm 1156 holds the stopper against theinlet 1162. When the actuating element 1126 is moved to an openposition, the actuating arm 1156 is moved away from the inlet 1162, andthe stopper 1135 is free to move to an open or neutral position whereinwater can flow through the inlet 1162 and into the outlet 1163. When theactuating element 1126 is in a failed state, similar to that which wasexplained above, the stopper 1135 is able to block the outlet 1163 andprevent water flow through the outlet 1163.

In operation, the actuating element 1126 is operable in three states,namely an open state, a closed state, and a failed state. The actuatingelement 1126 transitions between the open and closed states based on atemperature of the water at the bypass valve 1110. For example, the bodyof the actuating element 1126 expands and contracts based ontemperature. In the closed state, the wax or wax/copper mixture of theactuating element 1126 is expanded within the casing 1155, thus forcingthe casing 1155 away from the piston 1152 and toward the cheek valve1136. In the closed position, the actuating element 1126 is actuated toan extent such that the actuating arm 1156 forces the stopper 1135 toplug the inlet 1162 and restrict flow of water through the check valve1136. As the wax or wax/copper mixture of the thermal actuator 1126cools, the thermal actuator 1126 will, at some point, contract, and thebias spring 1128 forces the casing 1155 away from the check valve 1136.When the wax or wax/copper mixture contracts, the actuator arm 1156releases the stopper 1135 from the closed position and water flowsthrough the inlet 1162. In the failed state, the wax or wax/coppermixture no longer expands to an extent wherein the actuator arm 1156 ispositioned beyond the outlet 1163. Accordingly, the stopper 1135 is ableto freely move within the check valve 1136 to plug the inlet 1162 andthe outlet 1163, depending on the flow direction of the water throughthe bypass valve 1110.

FIG. 25 is a schematic view of an alternative bypass valve 1210 for usewithin the water distribution system 1067 shown in FIG. 20. The bypassvalve 1210 includes a valve unit 1212 and a control mechanism 1214. Thebypass valve 1210 is positioned between a hot water supply pipe on a hotside, indicated generally by H, and a cold water supply pipe on a coldside, indicated generally by C. Optionally, the bypass valve 1210 may bepositioned in a similar manner as described with reference to FIG. 20.The bypass valve 1210 may include four ports as described above, oralternatively, may include only two ports that interconnect with the hotand cold supply pipes. Flow through the bypass valve 1210 is generallyprovided from the hot side to the cold side to flush the cooled water inthe hot supply pipes and replenish that cooled water with hot water. Apump may be provided to channel the water through the system.Optionally, the valve unit 1212 may restrict water flow in a directionfrom the cold side to the hot side at all times.

The control mechanism 1214 is operable to control an operative state ofthe valve unit 1212. Optionally, the control mechanism 1214 may be athermostatic actuator, similar to the actuating elements describedabove. In alternative embodiments, the control mechanism 1214 may becontrolled by other methods or devices, such as electronicallycontrolled or controlled by devices other than a thermostatic actuator.In such embodiments, the control mechanism 1214 may be controlled basedon water characteristics such as temperature, flow, pressure, and thelike.

The valve unit 1212 is operable in three operative states; a closedstate, an open state and a failed state. In the closed state, the valveunit 1212 restricts flow from the hot side to the cold side. In the openstate, the valve unit 1212 allows flow from the hot side to the coldside. In the failed state, the valve unit 1212 restricts flow from thehot side to the cold side.

FIG. 26 is a side elevation view of an alternative bypass valve 1310 foruse within the water distribution system 1067 shown in FIG. 20 with aportion of a body 1312 of the bypass valve 1310 cutaway to illustratethe various components of the bypass valve 1310. The bypass valve 1310is operable in a first or closed state in which water is restricted fromflowing through the bypass valve 1310; a second or open state in whichwater is allowed to flow through the bypass valve 1310; and a third orfailed state in which water is retricted from flowing through the bypassvalve 1310. The bypass valve 1310 is illustrated in the second or openstate in FIG. 26.

The valve body 1312 includes a first body portion 1311 and a second bodyportion 1313. The body portions 1311, 1313 are joined to one another toform the valve body 1312. For example, pins 1315 may be used to hold thebody portions together. Alternatively, the body portions 1311, 1313 maybe threadably coupled to one another, or coupled together using othermethods such as welding. Optionally, a seal 1319 may be provided betweenthe body portions 1311, 1313 to resist leakage. In an alternativeembodiment, the body 1312 may be a unitary structure.

The body 1312 includes a first end 1314, a second end 1316 and aseparating wall 1317 disposed between the first end 1314 and the secondend 1316. Optionally, the separating wall 1317 may be separatelyprovided from the first and second body portions 1311, 1313.Alternatively, the wall 1317 may be formed integrally with, molded, ormanufactured into one or both of the body portions 1311, 1313. First end1314 is designated to receive and discharge hot water and second end1316 is designated to receive and discharge cold water from a source ofcold water, such as a city water supply system or a local water well. Atthe first end 1314 (the hot water side) is first inlet port 1318 andfirst discharge port 1320 and at the second end 1316 (the cold waterside) is second inlet port 1322 and second discharge port 1324. Theinlet and discharge ports are illustrated as female ports, but the inletand discharge ports may be male ports in alternative embodiments.Additionally, the ports may be threaded. The first 1318 and second 1322inlet ports connect to the hot and cold water distribution system andfirst 1320 and second 1324 discharge ports connect to the hot and coldwater valves on the fixture (e.g., sink, shower, bathtub, appliance, andthe like) with which the bypass valve 1310 is utilized. The bypass valve1310 may generally be used for a higher demand system as compared to thebypass valve 1010 or 1110 (shown in FIGS. 20-25), For example, theamount of water allowed to flow between the first and second ends 1314,1316 is greater than for the bypass valves 1010 or 1110 as the openingthrough the wall 1317 is larger. As such, the pump is capable ofchanneling the water through the pipe system more quickly when using thebypass valve 1310, or the pump is capable of channeling more waterthrough the pipe system when using the bypass valve 1310.

Valve body 1312 houses a thermally sensitive actuating element 1326, abias spring 1328, an over-travel spring 1330, a first spring retainer1332, a second spring retainer 1334, and a check valve 1336. In theillustrated embodiment, the spring retainers 1332, 1334 are separatelyprovided from and received within the body portions 1311, 1313,respectively. Alternatively, the spring retainers 1332, 1334 may beintegrally formed with, molded or manufactured into the body portions1311, 1313, respectively. The spring retainers 1332, 1334 are designedand positioned to allow water to flow through or around the springretainers 1332, 1334. Valve body 1312 is molded or manufactured to havea main passage 1338 for housing the various components of the valve1310, The main passage 1330 includes an internal shoulder 1340 forpositioning one end of first spring retainer 1332 and the main passage1330 includes an internal shoulder 1342 for positioning one end of thesecond spring retainer 1334. The valve body 1312 is designed so thecomponents can fit through the joined ends of the body portions 1311,1313 prior to joining the body portions 1311, 1313 to one another.

Optionally, thermally sensitive actuating element 1326 may be of the waxfilled cartridge type having a main body 1354 and an integral rod member1350 extending from the main body 1354. Rod member 1350 comprises apiston 1352 and a disk 1354 slidably coupled to the piston 1352. Thedisk 1354 is sized to substantially fill the passage 1338, or at least aportion of the passage, to restrict flow of water through the passage1338 when the disk 1354 is positioned at a predetermined position orpositions, such as at a forward-most position and a rearward-mostposition. For example, in the forward-most position, the disk 1354engages a forward wall portion 1356 of the valve body 1312; and in therearward-most position, the disk 1354 engages a rearward wall portion1358 of the valve body 1312. The forward wall portion 1356 is anecked-down section having a reduced diameter as compared to a centralportion 1360 of the passage 1338 between the forward and rearward wallsections 1356, 1358; and the rearward wall portion 1358 is a necked-downsection having a reduced diameter as compared to the central portion1360. Optionally, the rearward wall portion 1356 may be included withinthe wall 1317. Additionally, at least one position, and possibly manypositions are provided in which water is able to flow past the disk1354, such as when the disk 1354 is positioned within the centralportion 1360. Optionally, the disk 1354 may include an annular seal 1355around the perimeter of the disk 1354 to establish a seal between thedisk 1354 and the walls of the passage 1338. Optionally, the piston 1352may include at least one o-ring or snap ring 1357 that operates to limitthe range of motion of the disk 1354 along the piston 1352. In analternative embodiment, the disk 1354 may be fixedly coupled to, orintegrally formed with, the piston 1352. Optionally, the piston 1352includes a stepped-down portion 1353 proximate an end of the piston1352. The stepped down portion 1353 provides a shoulder for engaging thebias spring 1328.

Actuating element 1326 comprises a wax or a mixture of wax and metalpowder (e.g., copper powder). Upon heating, the wax or wax with copperpowder mixture slowly expands, thereby pushing against piston 1352 andforcing the piston 1352 in the hot side direction, indicated by arrow G.The piston 1352 is forced to the closed position wherein the disk 1354engages the valve body 1312 and stops water flow therethrough. Uponcooling, the wax or wax/copper powder mixture contracts and the biasspring 1328 forces the piston 1152 in the cold side direction, indicatedby arrow H. The piston 1352 is moved to a position wherein the disk 1354is moved away from the valve body 1312 and water is allowed to flow fromthe hot side to the cold side. Optionally, as described above, the disk1354 is free to move along the piston 1352. For example, when a negativehead is created on the hot side, such as when the hot water is turnedon, the water tends to flow from the cold side to the hot side. The disk1354 is moved in the hot side direction, indicated by arrow G, along thepiston 1352 until the disk 1354 engages the valve body 1312, thusrestricting flow of water from the cold side to the hot side even whenthe actuator 1326 is in the contracted position.

In operation, the actuating element 1326 is operable in three states,namely an open state, a closed state, and a failed state. The actuatingelement 1326 transitions between the open and closed states based on atemperature of the water at the bypass valve 1310. For example, the bodyof the actuating element 1326 expands and contracts based ontemperature. In the closed state, the wax or wax/copper mixture of theactuating element 1326 is expanded, thus forcing the piston 1352 towardthe forward wall portion 1356 of the valve body 1312. In the closedposition, the actuating element 1326 is actuated to an extent such thatthe piston 1352 forces the disk 1354 to plug the passage 1338 andrestrict flow of water therethrough. As the wax or wax/copper mixture ofthe thermal actuator 1326 cools, the thermal actuator 1326 will, at somepoint, contract, and the bias spring 1328 forces the piston toward therearward wall portion 1358. When the wax or wax/copper mixturecontracts, the piston 1352 releases the disk 1354 from the closedposition and water flows through the passage 1338. In the failed state,the wax or wax/copper mixture no longer expands to an extent wherein thedisk 1354 is positioned away from the rearward wall portion 1358.Accordingly, the disk 1354 engages the rearward wall portion 1358 toplug the passage 1338. As such, the disk 1354 and valve body 1312constitute a check valve and operate in a similar manner as the checkvalve 1036 described above.

Actuating element 1326 comprises a wax or a mixture of wax and metalpowder (e.g., copper powder). Upon heating, the wax or wax with copperpowder mixture slowly expands, thereby pushing against piston 1352 andforcing the piston 1352 in the hot side direction, indicated by arrow G.The piston 1352 is forced to the closed position wherein the disk 1354engages the valve body 1312 and stops water flow therethrough. Uponcooling, the wax or wax/copper powder mixture contracts and the biasspring 1328 forces the piston 1152 in the cold side direction, indicatedby arrow H. The piston 1352 is moved to a position wherein the disk 1354is moved away from the valve body 1312 and water is allowed to flow fromthe hot side to the cold side. Optionally, as described above, the disk1354 is free to move along the piston 1352. For example, when a negativehead is created on the hot side, such as when the hot water is turnedon, the water tends to flow from the cold side to the hot side. The disk1354 is moved in the hot side direction, indicated by arrow G, along thepiston 1352 until the disk 1354 engages the valve body 1312, thusrestricting flow of water from the cold side to the hot side even whenthe actuator 1326 is in the contracted position.

In operation, the actuating element 1326 is operable in three states,namely an open state, a closed state, and a failed state. The actuatingelement 1326 transitions between the open and closed states based on atemperature of the water at the bypass valve 1310. For example, the bodyof the actuating element 1326 expands and contracts based ontemperature. In the closed state, the wax or wax/copper mixture of theactuating element 1326 is expanded, thus forcing the piston 1352 towardthe forward wall portion 1356 of the valve body 1312. In the closedposition, the actuating element 1326 is actuated to an extent such thatthe piston 1352 forces the disk 1354 to plug the passage 1338 andrestrict flow of water therethrough. As the wax or wax/copper mixture ofthe thermal actuator 1326 cools, the thermal actuator 1326 will, at somepoint, contract, and the bias spring 1328 forces the piston toward therearward wall portion 1358. When the wax or wax/copper mixturecontracts, the piston 1352 releases the disk 1354 from the closedposition and water flows through the passage 1338. In the failed state,the wax or wax/copper mixture no longer expands to an extent wherein thedisk 1354 is positioned away from the rearward wall portion 1358.Accordingly, the disk 1354 engages the rearward wall portion 1358 toplug the passage 1338. As such, the disk 1354 and valve body 1312constitute a check valve and operate in a similar manner as the checkvalve 1036 described above.

While there is shown and described herein certain specific alternativeforms of the invention, it will be readily apparent to those skilled inthe art that the invention is not so limited, but is susceptible tovarious modifications and rearrangements in design and materials withoutdeparting from the spirit and scope of the invention. In particular, itshould be noted that the present invention is subject to modificationwith regard to the dimensional relationships set forth herein andmodifications in assembly, materials, size, shape, and use, and thevarious features from the various embodiments may be interchangedwithout departing from the spirit and scope of the invention.

What is claimed is:
 1. A bypass valve comprising: a housing having a hotwater port configured to communicate with a hot water supply line and areturn port configured to discharge water from the housing forrecirculation to a hot water source, the housing having a passagepermitting recirculating flow between the hot water port and the returnport; and a valve member operable to allow and restrict recirculatingflow through the passage, the valve member restricting water flowthrough the passage in a failed state.
 2. A bypass valve in accordancewith claim 1, further comprising a control mechanism operatively coupledto the valve member.
 3. A bypass valve in accordance with claim 2,wherein the control mechanism is housed within the housing.
 4. A bypassvalve in accordance with claim 2, wherein the control mechanismcomprises a thermally sensitive actuating element.
 5. A bypass valve inaccordance with claim 1, wherein the valve member is controlled based onat least one of a flow switch, a pressure switch, a temperature switchand a manual switch.
 6. A bypass valve in accordance with claim 1,wherein the valve member comprises a check valve having a stopper.
 7. Abypass valve in accordance with claim 1, wherein the return port isconfigured to discharge water into a cold water supply line, the valvemember allowing water to flow from the hot water supply line to the coldwater supply line when the valve unit is operating in an open state. 8.A bypass valve in accordance with claim 1, wherein the valve member isconfigured to be positioned adjacent a fixture.
 9. A bypass valve inaccordance with claim 1, wherein the valve member is configured to bepositioned in a fixture.
 10. A bypass valve in accordance with claim 1,further comprising a control mechanism operatively coupled to the valvemember, the control mechanism including an actuating element beingmovable within the housing, the actuating element interacting with thevalve member in an unfailed state, the actuating element not interactingwith the valve member in the failed state.
 11. A bypass valvecomprising: a housing having a hot water port configured to communicatewith a hot water supply line and a cold water port configured tocommunicate with a cold water supply line, the housing having a passagepermitting recirculating flow between the hot and cold water ports; anda valve member operable to allow and restrict recirculating flow throughthe passage, the valve member restricting water flow through the passagein a failed state.
 12. A bypass valve in accordance with claim 11,further comprising a control mechanism operatively coupled to the valvemember.
 13. A bypass valve in accordance with claim 12, wherein thecontrol mechanism is housed within the housing.
 14. A bypass valve inaccordance with claim 12, wherein the control mechanism comprises athermally sensitive actuating element.
 15. A bypass valve in accordancewith claim 11, wherein the valve member is controlled based on at leastone of a flow switch, a pressure switch, a temperature switch and amanual switch.
 16. A bypass valve in accordance with claim 11, whereinthe valve member comprises a check valve having a stopper.
 17. A bypassvalve in accordance with claim 11, wherein the valve member isconfigured to be positioned adjacent a fixture.
 18. A bypass valve inaccordance with claim 11, wherein the valve member is configured to bepositioned in a fixture.
 19. A bypass valve in accordance with claim 11,further comprising a control mechanism operatively coupled to the valvemember, the control mechanism including an actuating element beingmovable within the housing, the actuating element interacting with thevalve member in an unfailed state, the actuating element not interactingwith the valve member in the failed state.
 20. A bypass valve for use ina bypass path of a water circulation system, the bypass valvecomprising: a valve member operable to allow and restrict recirculatingflow through the bypass path, the valve member restricting water flowthrough the bypass path in a failed state; and a control mechanism inthe bypass path of the water circulation system, the control mechanismused for controlling the operation of the valve unit.
 21. A bypass valvein accordance with claim 20, wherein water flowing through the bypasspath flows past the control mechanism.
 22. A bypass valve in accordancewith claim 20, wherein the control mechanism comprises a thermallysensitive actuating element.
 23. A bypass valve in accordance with claim20, wherein the control mechanism is controlled based on at least one ofa flow switch, a pressure switch, a temperature switch and a manualswitch.
 24. A bypass valve in accordance with claim 20, wherein thecontrol mechanism includes an actuating element configured to engage thevalve member, the actuating element interacting with the valve member inan unfailed state, the actuating element not interacting with the valvemember in the failed state.